Coefficient of the static friction homework

[touma]

A large cube with a mass of 25 kg is being accelerated across a horizontal frictionless surface by a horizontal force P. A small cube with a mass of 4.0 kg is in contact with the front surface of the large cube and will slide downwards unless P is sufficiently large. The coefficient of the static friction between the cubes is 0.71. What is the smallest magnitude that P can have in order to keep the small cubbe from cliding downward?


I got an answer of 4.0 x 10^2 N. But I am unsure if that is correct. Can someone try this? And show work please?

 

[OlderDan]

Can someone try this? And show work please?

It really does not work that way here. You show your work and then people will help you.